Heat transfer enhancement of micro oscillating heat pipes with self-rewetting fluid

This paper discusses the heat transfer enhancement of micro oscillating heat pipes (MOHPs) using self-rewetting fluid (SRWF). To clarify the heat transfer enhancement mechanism, the thermo-physical properties (including surface tensions, contact angles and thermal conductivities) of SRWFs and deionized water have been comparatively analyzed. Furthermore, to find out the strengthening effect, experimental studies were performed on MOHPs. During the experiments, MOHPs with heat transfer length (L) of 100, 150 and 200 mm, consisting of 4 meandering turns and inner diameter (Di) of 0.4, 0.8, 1.3 mm were adopted. SRWF and deionized water were employed as the working fluids. The results showed that, due to the unique property that the surface tension increases with increasing temperature, the SRWF can spontaneously wet the hotter region. The capillary resistance of the SRWF was much smaller than that of the deionized water, which is conductive to improving the circulation efficiency of the working fluid. Compared with the water, as the working fluid of the MOHPs, the SRWF exhibited much better thermal performance, which can decrease the thermal resistance and extend the effective operation range of MOHPs.